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Making Open Access Book Funding Work Fairly: Opening the Future library membership scheme & publisher toolkit
No full textA talk to the Association of University Presse
Is Negative E-WOM more powerful? Multimodal data analysis on air passengers’ perception of COVID safety measures
Get PDFDuring the normalization stage of the COVID-19 epidemic prevention and control, the safety threats caused by improper epidemic prevention measures of airlines have become the primary concern for air passengers. Negative e-WOM related to safety perception obtained based on online multimodal reviews of travel websites has become an important decision-making basis for potential air passengers when making airline choices. This study aims to examine the relationship between potential air passengers’ negative safety perception and the usefulness of online reviews, as well as to test the moderating effect of review modality and airline type. It also further explores the effectiveness and feasibility of applying big data sentiment analysis to e-WOM management. To this end, the theoretical model of negative safety perception, review modality, and airline type affecting review usefulness was constructed. Then we select 10 low-cost airlines and 10 full-service airlines, respectively, according to the number of reviews sorted by the TripAdvisor website, and use crawling techniques to obtain 10,485 reviews related to COVID-19 safety of the above companies from December 2019 to date, and conduct safety perception sentiment analysis based on Python’s Textblob library. Finally, to avoid data overdispersion, the model is empirically analyzed by negative binomial regression using R software. The results indicate that (1) Negative safety perception significantly and negatively affects review usefulness, that is, extreme negative safety perception can provide higher review usefulness for potential air passengers. (2) Review modality and airline type have a significant moderating effect on the relationship between negative safety perception and review usefulness, in which multimodal reviews and full-service airlines both weakened the negative impact of negative safety perception on review usefulness. The theoretical model in this paper is both an extension of the application of big data sentiment analysis techniques and a beneficial supplement to current research findings of e-WOM, providing an important reference for potential air passengers to identify useful reviews accurately and thus reduce safety risks in online decision-making
Risk contributions of lambda quantiles
Get PDFRisk contributions of portfolios form an indispensable part of risk adjusted performance measurement. The risk contribution of a portfolio, e.g., in the Euler or Aumann-Shapley framework, is given by the partial derivatives of a risk measure applied to the portfolio profit and loss in direction of the asset units. For risk measures that are not positively homogeneous of degree 1, however, known capital allocation principles do not apply. We study the class of lambda quantile risk measures that includes the well-known Value-at-Risk as a special case but for which no known allocation rule is applicable. We prove differentiability and derive explicit formulae of the derivatives of lambda quantiles with respect to their portfolio composition, that is their risk contribution. For this purpose, we define lambda quantiles on the space of portfolio compositions and consider generic (also non-linear) portfolio operators.
We further derive the Euler decomposition of lambda quantiles for generic portfolios and show that lambda quantiles are homogeneous in the space of portfolio compositions, with a homogeneity degree that depends on the portfolio composition and the lambda function. This result is in stark contrast to the positive homogeneity properties of risk measures defined on the space of random variables which admit a constant homogeneity degree. We introduce a generalised version of Euler contributions and Euler allocation rule, which are compatible with risk measures of any homogeneity degree and non-linear but homogeneous portfolios.
These concepts are illustrated by a non-linear portfolio using financial market data
The U, V and W polynomials
No full textThis chapter covers the U-, W-, V- and strong U-polynomials, generalizations of the Tutte polynomial.
• The definitions of the U-, W-, V- and strong U-polynomials.
• Basic theory including expansions of the polynomials and evaluations.
• The equivalence of U with Stanley’s symmetric Tutte function and Brylawski’s polychromate.
• The problem of deciding whether non-isomorphic trees can have the same
U-polynomial.
• Complexity issues.
• Other related polynomials.
Book synopsis: The Tutte Polynomial touches on nearly every area of combinatorics as well as many other fields, including statistical mechanics, coding theory, and DNA sequencing. It is one of the most studied graph polynomials.
Handbook of the Tutte Polynomial and Related Topics is the first handbook published on the Tutte Polynomial. It consists of thirty-four chapters written by experts in the field, which collectively offer a concise overview of the polynomial’s many properties and applications. Each chapter covers a different aspect of the Tutte polynomial and contains the central results and references for its topic. The chapters are organized into six parts. Part I describes the fundamental properties of the Tutte polynomial, providing an overview of the Tutte polynomial and the necessary background for the rest of the handbook. Part II is concerned with questions of computation, complexity, and approximation for the Tutte polynomial; Part III covers a selection of related graph polynomials; Part IV discusses a range of applications of the Tutte polynomial to mathematics, physics, and biology; Part V includes various extensions and generalizations of the Tutte polynomial; and Part VI provides a history of the development of the Tutte polynomial.
Features
Written in an accessible style for non-experts, yet extensive enough for experts
Serves as a comprehensive and accessible introduction to the theory of graph polynomials for researchers in mathematics, physics, and computer science
Provides an extensive reference volume for the evaluations, theorems, and properties of the Tutte polynomial and related graph, matroid, and knot invariants
Offers broad coverage, touching on the wide range of applications of the Tutte polynomial and its various specialization
Violin varnishes: microstructure and nanomechanical analysis
Get PDFThe aim of the current work is twofold: to demonstrate the application of in situ non-invasive imaging by portable atomic force microscopy (AFM) on the surfaces of a violin and to integrate compositional and mechanical analysis at the nano scale level on model samples of varnished wood. These samples were prepared according to traditional recipes by an Italian lutemaker family well practised in the art. Samples of oil and spirit-based varnishes on maple wood, naturally and accelerated light aged, were studied. AFM was used to measure the nanomechanical properties of the model samples and established that the spirit-based varnish was stiffer than the oil-based. Synchrotron radiation micro- Fourier Transform Infra-red analysis of the layer structure revealed that stiffer spirit-based varnish showed less penetration into the wood than the oil-based. Further PeakForce Quantitative Nanomechanical Mapping (QNM) demonstrated a difference in adhesion values between the oil- and spirit-based sample
Supply of drugs in prison
Get PDFBook synopsis: This publication provides an overview of current knowledge and the latest developments in the field of drug use and prison in Europe. The report explores in depth the epidemiology of drug use and drug-related problems among the prison population, the available social and health service responses to drug-related problems in prison, including the most recent evidence of effectiveness, and the drug supply and markets inside prison. It also discusses recent and future challenges in this area. The report will be of interest to policymakers and their advisors, specialists and practitioners, researchers and scientists and all those concerned with the issue of prison and drugs
Levels of foreign language enjoyment, anxiety and boredom in emergency remote teaching and in in-person classes
Get PDFThe present mixed-method study focuses on levels of foreign language enjoyment (FLE), foreign language classroom anxiety (FLCA) and foreign language boredom (FLB) among 168 Arab and Kurdish English as a foreign language (EFL) learners in both in-person and emergency remote teaching (ERT) classes. Statistical analyses revealed that learners experienced significantly more FLE, more FLCA, and less FLB in in-person classes than in ERT classes. The qualitative data revealed a more nuanced picture about the things learners appreciated and disliked in both contexts. Sitting at home in front of their computer, many learners did feel more isolated, disengaged, distracted, and missed the interactions with peers and teacher. Yet, some participants felt that ERT did allow relationship-building, lessened their fear of making errors and pushed them to develop new coping strategies. The main sources of FLCA in ERT turned out to be issues with internet connection rather the anxiety of making errors in front of everybody. Boredom arose mostly from a lack of exciting social interactions and monotony in delivery which could induce disengagement. Some pedagogical implications are presented
Pupil size and pupillary light reflex in early infancy: heritability and link to genetic liability to schizophrenia
Get PDFBackground: Measures based on pupillometry, such as the pupillary light reflex (PLR) and baseline pupil size, reflect physiological responses linked to specific neural circuits that have been implicated as atypical in some psychiatric and neurodevelopmental conditions.
Methods: We investigated the contribution of genetic and environmental factors to the baseline pupil size and the PLR in 510 infant twins assessed at 5 months of age (281 monozygotic and 229 dizygotic pairs), and its associations with common genetic variants associated with neurodevelopmental (autism spectrum disorder and attention deficit hyperactivity disorder) and mental health (bipolar disorder, major depressive disorder and schizophrenia) conditions using genome-wide polygenic scores (GPSs).
Results: Univariate twin modelling showed high heritability at 5 months for both pupil size (h2 = .64) and constriction in response to light (h2 = .62), and bivariate twin modeling indicated substantial independence between the genetic factors influencing each (rG = .38). A statistically significant positive association between infant tonic pupil size and the GPS for schizophrenia was found (β = .15, p = .024), while there was no significant association with the GPS for autism or any other GPSs.
Conclusions: This study shows that some pupil measures are highly heritable in early infancy, although substantially independent in their genetic etiologies, and associated with common genetic variants linked to schizophrenia. It illustrates how genetically informed studies of infants may help us understand early physiological responses associated with psychiatric disorders which emerge much later in life
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